The invention concerns a supply air terminal device.
The state of the art knows so-called heating and cooling manifolds, through which room air is circulated and through which fresh outdoor air is also brought mixed with the room air into the room space. With the above-mentioned devices the room air can be cooled in summer and heated in winter. In the heating case, a heat exchanger can be equipped with a two-sided circuit for circulating a heat carrier, wherein in one circuit a heat carrier is transported for cooling and wherein in the other circuit a heat carrier is transported for heating. Such an embodiment is also possible, that one and the same tube system is used for both purposes. In certain cases there is only a cooling tube system and the heating is carried out by separate heat resistances, which are placed in connection with a heat exchanger and in spaces between heat-exchanging tubes.
The primary air can be heated by a separate duct heater. When the primary airflow rate is relatively low, this leads to rather high supply air temperatures, and the heater must also be equipped with an overheating protector as safety equipment.
There are air-conditioning manifolds on the market, where electric heating is implemented by installing an electric resistance inside the heat exchanger. In order to achieve sufficient efficiency, the resistance must be designed so that the surface temperature of the resistance will rise easily to hundreds of degrees, whereby the device must be provided with overheating protections.
Such air-conditioning manifolds are also on the market, where a heating film is glued directly on to the device's outer or inner surface, whereby elimination of thermal expansion has been a challenging task.